1. Technical Field
The disclosure generally relates to the electronic display of documents. More particularly, the disclosure relates to the rendering of the thickness of annotations in electronically displayed documents.
2. Related Art
Many factors today drive the development of computers and computer software. One of these factors is the desire to provide accessibility to information virtually anytime and anywhere. The proliferation of notebook computers, personal digital assistants (PDAs), and other personal electronic devices reflect the fact that users want to be able to access information wherever they may be, whenever they want. In order to facilitate greater levels of information accessibility, the presentation of information must be made as familiar and comfortable as possible.
In this vein, one way to foster success of electronic presentations of information will be to allow users to handle information in a familiar manner. Stated another way, the use and manipulation of electronically-presented information may mimic those paradigms that users are most familiar with, e.g., printed documents, as an initial invitation to their use. As a result, greater familiarity between users and their “machines” will be engendered, thereby fostering greater accessibility, even if the machines have greater capabilities and provide more content to the user beyond the user's expectations. Once users feel comfortable with new electronic presentations, they will be more likely to take advantage of an entire spectrum of available functionality.
One manner of encouraging familiarity is to present information in an electronic book format in which a computer displays information in a manner that closely resembles printed books. In order to more completely mimic a printed book, users will need to have the ability to make textual notes to themselves, akin to writing in the margins of paper books. Users will also want to highlight selected portions, as these are active-reading activities of which a user would expect to see in an electronic book. Users will want to add drawings, arrows, underlining, strike-throughs, and the like, also akin to writing in paper books. Finally, users will want to add bookmarks.
The above-identified so-called “active-reading” activities are available. However, all of these active-reading activities require modification of the underlying document. For example, as is known in the art, if one adds a comment or annotation in an electronic editor, the comment or annotation is inserted into the document. This insertion corrupts the underlying document from its pre-insertion, pristine state. While this may not be an issue in an editable document, the modification of a copyrighted document may run afoul of various copyright provisions. The violations may be compounded with the forwarding of the document to another in its modified state. Further, irrespective of any copyright transgressions, publishing houses responsible for the distribution of the underlying text may not be pleased with any ability to modify their distributed and copyrighted works.
Thus, the users' desire to actively read and annotate works clashes with the goals of publishing houses to keep copyrighted works in their unmodified state. Without solution of this dilemma, the growth of the electronic publishing industry may be hampered, on one hand, by readers who refuse to purchase electronic books because of the inability to annotate read-only documents and, on the other hand, by the publishing industry that refuses to publish titles that allow for annotations that destroy the pristine compilation of the electronic works.
Further, user's who are able to add hand written annotations or drawings (also referred to herein as “ink annotations”) need to be able to see the annotations without difficulty. In order for ink annotations to “look good” and provide users with good, useful, functionality (especially for making notes and the like), the rendered ink line-widths need to be smooth looking, not too thin, and not too thick. Existing algorithms for improving line-smoothness tend to trade off between complexity and quality (the simpler methods do not produce lines that look as good while the more complex methods have implementation and execution-speed overhead for producing better quality lines). What is needed is a relatively simple method for rendering smooth looking lines that imposes a small load on processing resources.